Successful trial assembly of reactor vessel for India’s Kudankulam plant unit 5  

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A trial assembly of the internals of the reactor pressure vessel (RPV) designated for unit 5 of India’s Kudankulam nuclear power plant (KNPP) was successfully undertaken in late January 2023 at the Volgodonsk (Russia) plant of Atommash, which is a subsidiary of Atomenergomash, the machine building division of the Russian state atomic energy corporation Rosatom. 

A Rosatom statement said the check assembly was carried out using an underground caisson, or hollow in the concrete floor, that simulates the position the vessel will hold in the real power plant. First, specialists using a crane with a lifting capacity of 600 tonnes installed the 11-metre VVER-1000 RPV in its design position. Next, one by one, a 10-metre core barrel weighing 73 tonnes, a core baffle of 38 tonnes, and a block of protective pipes weighing 68 tonnes were lowered inside. The nuclear reactor was then closed with a standard lid. The total weight of the assembled product was 603 tonnes. 

“During the assembly, the staff installed keys and fasteners on the Reactor Vessel and fixed the centering device of the reactor cover. During check assembly, the items exactly repeat their design position,” the statement said. 

A control assembly, in which the products completely replicate their design position, significantly reduces the installation time and simplifies the process of installation of the reactor at the NPP construction site, the statement added.  

The reactor pressure vessel is the heart of a nuclear power plant. It contains the nuclear fuel assemblies which produce heat and forms part of the primary coolant circuit. It also contains provisions for sensors and moving parts such as control rods. 

Rosatom is the equipment supplier and technical consultant for the KNPP, India’s largest nuclear plant operated by the state-run Nuclear Power Corporation of India Ltd. Its units 1 and 2, of 1,000 MW capacity each, started commercial operations in 2014 and 2016, respectively. Rosatom is similarly collaborating in the construction of four more VVER-1000 type units at Kudankulam – 3, 4, 5 and 6 – of 1,000 MW capacity each.  Kudankulam is located in Tamil Nadu state in south India.    

In a separate statement, Rosatom said that Atommash has successfully tested another key component of the primary circuit of KNPP’s unit 5 – its pressuriser, which helps maintain the appropriate pressure of the coolant water used to transfer heat from fuel assemblies in the reactor pressure vessel to the steam generators. “The pressure in the tank was increased to the maximum allowable value for this equipment, which is 24.7 MPa (Megapascals),” the statement said, adding that the equipment is being prepared for shipment.